1. Field of the Invention
This invention relates to an apparatus for mechanically breaking up rock including a single slider wedge which is reciprocable by means of a hydraulically operated actuator etc.
2. Description of the Prior Art
In a convetional rock breaking apparatus wherein wedge guides divided into halves are inserted into a hole which has previously been drilled in a rock to be broken up by means of a hydraulic drill etc., and a single wedge which is reciprocable by means of a hydraulic actuator etc. is thrusted in between the wedge guides to spread the latter thereby breaking up the rock, bellow-shaped dust-proof membranes capable of expansion and contraction are mounted to extend between the opposite surfaces of the afore-mentioned divided wedge guide halves to prevent the earth and sand from entering into the space between the wedge guides.
In that case, the conventional dust-proof membranes are constructed as follows. Stating in brief, the opposed surfaces of the divided wedge guide halves are formed with dovetail grooves in which round bars formed at both side edges of each dust-proof membrane are thrusted in to thereby attach the latter or, as an alternative, a wire is inserted into each of the side edges of the respective membranes, and then terminals formed in both ends of each of the wires are thrusted into the respective dovetail grooves to attach the membranes. However, the former method is disadvantageous in that it is difficult to thrust the round bars into the dovetail grooves, respectively, whilst the latter method is also disadvantageous in that it is difficult to keep the wires taut in the dovetail grooves, and when wires become loose the earth and sand tends to enter into the space between the wedge guide halves through the wire portions.
The conventional rock breaking apparatus is further disadvantageous in that, when the slider wedge is thrusted in between the wedge guides to break up the rock, the leading end of the slider wedge is projected from the tips of the wedge guides and driven into rock debris accumulating the bottom of the hole in the rock thereby causing a damage of the slider wedge, or the crushed rock debris will deposit on the sliding surfaces of the slider wedge thus causing stocking of the latter between the wedge guides.